package com.homework.util;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import org.apache.poi.hwpf.extractor.WordExtractor;

public class SimilarityCheck {

	private BufferedReader br;

	/**
	 * 计算相似度
	 * 
	 * @param file1
	 * 
	 * @param file2
	 * 
	 * @return int
	 */
	public int Compare(String filename1, String filename2) {
		String str = getHomework(filename1);
		String target = getHomework(filename2);
		int d[][]; // 矩阵
		int n = str.length();
		int m = target.length();
		int i; // 遍历str的
		int j; // 遍历target的
		char ch1; // str的
		char ch2; // target的
		int temp; // 记录相同字符,在某个矩阵位置值的增量,不是0就是1
		if (n == 0) {
			return m;
		}
		if (m == 0) {
			return n;
		}
		d = new int[n + 1][m + 1];
		for (i = 0; i <= n; i++) { // 初始化第一列
			d[i][0] = i;
		}

		for (j = 0; j <= m; j++) { // 初始化第一行
			d[0][j] = j;
		}

		for (i = 1; i <= n; i++) { // 遍历str
			ch1 = str.charAt(i - 1);
			// 去匹配target
			for (j = 1; j <= m; j++) {
				ch2 = target.charAt(j - 1);
				if (ch1 == ch2) {
					temp = 0;
				} else {
					temp = 1;
				}

				// 左边+1,上边+1, 左上角+temp取最小
				d[i][j] = min(d[i - 1][j] + 1, d[i][j - 1] + 1, d[i - 1][j - 1]
						+ temp);
			}
		}
		float tmp = 1 - (float) d[n][m] / Math.max(str.length(), target.length());
		int result = (int)(100*tmp);
		return result;
	}

	private int min(int one, int two, int three) {
		return (one = one < two ? one : two) < three ? one : three;
	}

	public String getHomework(String fileName) {
		StringBuffer sb = new StringBuffer();
		try {
			File f = new File(fileName);
			if (!f.exists()) {
				return "";
			}
			// 处理txt文件
			if (f.getName().endsWith(".txt")) {
				InputStreamReader isr = new InputStreamReader(
						new FileInputStream(f), "GB2312");
				br = new BufferedReader(isr);
				String line = "";
				while ((line = br.readLine()) != null) {
					sb.append(line);
				}
				return sb.toString();
			}
			// 处理word文件
			if (f.getName().endsWith(".doc") || f.getName().endsWith(".docx")
					|| f.getName().endsWith(".wps")) {
				FileInputStream fis = new FileInputStream(fileName);
				WordExtractor wordExtractor = new WordExtractor(fis);
				return wordExtractor.getText();
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "";
	}
}
